SHELBY COUNTY, Ala. – Officials on the scene say eight to nine Colonial Pipeline subcontractors were working on the gas pipeline trying to flush out one of the lines when it exploded, Shelby County Sheriff Maj. Ken Burchfield confirmed. AL.com reports Colonial has now shut down both pipelines running through the area.

A temporary flight restriction is in effect in the area of the pipeline explosion. Only relief aircraft are authorized in the airspace. pic.twitter.com/Ymld4xL3n4

According to WIAT, several cleanup units are on the scene. Birmingham fire is providing foam. At least seven people were injured in the explosion and some are believed to be severely burned. A UAB Hospital spokesman confirmed three patients were flown to UAB in the afternoon, three more were coming by ambulance and one more was coming by air, according to our news partner AL.com.

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Several injured in Alabama gas line explosion

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Several injured in Alabama gas line explosion

Flames shoot into the sky from a gas line explosion in western Shelby County, Alabama, U.S., October 31, 2016.

(REUTERS/Marvin Gentry)

New video shows fiery scene of gas explosion in Shelby County https://t.co/6JjMNC6sce https://t.co/8MrK4zGOLZ

Smoke rises into the sky from a gas line explosion in western Shelby County, Alabama, U.S., October 31, 2016. REUTERS/Marvin Gentry

Stunning view of Colonial pipeline explosion fire from @AlabasterFire. God bless the first responders on this scene. https://t.co/im0hnzQJr8

In addition to the injured victims, Shelby County Sheriff John Samaniego said there's a possibility that two workers are still missing. The heat from the blaze, he said, is hindering the search for them. Flames are still reaching about 50 feet in the air.

Colonial Pipeline says in a statement that it has shut down its main pipeline in Alabama after an explosion in a rural part of the state outside Birmingham. The Georgia-based company said in the brief statement Monday evening that its top priorities are the health and safety of its work crews at the scene and protecting the public. The company's statement did not address how Monday's explosion might affect the availability of gasoline and said more information would be released as it becomes available.

The Alabama Forestry Commission reports there are a total of three wildfires as a result of the explosion. Officials say no structures are directly threatened at this time. The Forestry Commission has three bulldozers and eight firefighters on the scene.